【GMAT考满分阅读RC题库】Recently biologists have been interested in a tide_真题_答案

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Recently biologists have been interested in a tide-associated periodic behavior displayed by the diatom Hantzschia virgata, a microscopic golden-brown alga that inhabits that portion of a shoreline washed by tides (the intertidal zone). Diatoms of this species, sometimes called "commuter" diatoms, remain burrowed in the sand during high tide, and emerge on the sand surface during the daytime low tide. Just before the sand is inundated by the rising tide, the diatoms burrow again. Some scientists hypothesize that commuter diatoms know that it is low tide because they sense an environmental change, such as an alteration in temperature or a change in pressure caused by tidal movement. However, when diatoms are observed under constant conditions in a laboratory, they still display periodic behavior, continuing to burrow on schedule for several weeks. This indicates that commuter diatoms, rather than relying on environmental cues to keep time, possess an internal pacemaker or biological clock that enables them to anticipate periodic changes in the environment. A commuter diatom has an unusually accurate biological clock, a consequence of the unrelenting environmental pressures to which it is subjected; any diatoms that do not burrow before the tide arrives are washed away.

This is not to suggest that the period of this biological clock is immutably fixed. Biologists have concluded that even though a diatom does not rely on the environment to keep time, environmental factors—including changes in the tide's hydrostatic pressure, salinity, mechanical agitation, and temperature—can alter the period of its biological clock according to changes in the tidal cycle. In short, the relation between an organism's biological clock and its environment is similar to that between a wristwatch and its owner: the owner cannot make the watch run faster or slower, but can reset the hands. However, this relation is complicated in intertidal dwellers such as commuter diatoms by the fact that these organisms are exposed to the solar-day cycle as well as to the tidal cycle, and sometimes display both solar-day and tidal periods in a single behavior. Commuter diatoms, for example, emerge only during those low tides that occur during the day.

According to the passage, each of the following is characteristic of the tide-associated periodic behavior of commuter diatoms EXCEPT:

AIt is triggered when the diatoms are inundated by the tide.
BIt is correlated with the rise and fall of the tide.
CIt adjusts to changes in the tidal cycle.
DIt is influenced by the solar-day cycle.
EIt is regulated by an innate time-keeping mechanism.

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正确答案: A

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oioioio

吃了没文化的亏

2016-10-07 16:47:46 IP属地：北京举报

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PriscillaWEI

Just before the sand is inundated by the rising tide, the diatoms burrow again.

2017-08-06 14:21:58 IP属地：甘肃举报

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花舞街云

不是diatoms被潮汐淹没时才会触发，它在大潮来之前就会钻进洞里。是它适应潮汐变化（高潮，低潮）而产生的period。

2016-07-09 15:32:35 IP属地：北京举报

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柰子55555

Just before the sand is inundated by the rising tide, the diatoms burrow again.

2015-12-02 09:58:28 IP属地：山东举报

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克村

E 的定位在 This indicates that commuter diatoms, rather than relying on environmental cues to keep time, possess an internal pacemaker or biological clock that enables them to anticipate periodic changes in the environment.

注意E选项中的innate = internal

A是正确选项，定位于 Some scientists hypothesize that commuter diatoms know that ... However, when diatoms are observed under constant conditions in a laboratory,

2016-05-30 02:27:12 IP属地：法国举报

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ruserious

This indicates that commuter diatoms, rather than relying on environmental cues to keep time, possess an internal pacemaker or biological clock that enables them to anticipate periodic changes in the environment

2013-12-16 22:08:27 IP属地：中国台湾举报

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danislj1227126

remain burrowed in the sand during high tide, and emerge on the sand surface during the daytime low tide.
潮汐淹没的时候，burrow，落的时候出来。不仅仅是潮汐淹没这一个行为引发

2016-05-25 22:09:45 IP属地：美国举报

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欧小鸥

D的内容在最后一句话里面提到了

2015-05-01 19:28:08 IP属地：北京举报

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沃要上700

尼玛是沙子被淹没啊喂

2016-12-01 19:35:38 IP属地：广西举报

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我代表沧海

我认为这道题相当不严谨，对于A没什么好说的，一看就知道是错误的，但是对于E，innate这个词在文章中根本没有一处体现，至于楼上有人说internal=innate,内部的怎么可能和天生的划上等号？高中学过生物学的都知道天生强调的是一生下来就拥有的“天赋”，而这篇文章无不在表现环境对生物的影响，就算真的在科学上是天生的，但是文章中完全没有提到。

2016-12-13 09:11:12 IP属地：湖北举报

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smallbk413 回复我代表沧海

internal=innate没有毛病，比如internal clock=innate clock都是生物钟

2017-09-02 15:53:30 IP属地：北京举报

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正确率： 56%

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